Should a patient with normal vitamin B12 and folic acid levels continue their current B12 and folic acid supplements?

Discontinue Both Supplements Immediately

Given your B12 level of 990 pg/mL (well above the normal range of 180-350 pg/mL) and folic acid level of 21 ng/mL (significantly elevated above normal range of 2.7-17 ng/mL), you should stop both supplements. These levels indicate excessive supplementation without clear benefit, and continuing poses potential risks without documented deficiency 1.

Why Stop Supplementation Now

B12 Levels Are Excessively High

• Your B12 level of 990 pg/mL is nearly triple the upper threshold of 350 pg/mL used to rule out deficiency 2
• Serum B12 >350 pg/mL makes deficiency unlikely and does not require supplementation 2
• There is no evidence that maintaining supraphysiologic B12 levels provides additional benefit in patients without documented deficiency or malabsorption 2

Folic Acid Levels Are Also Elevated

• Your folic acid level of 21 ng/mL exceeds normal ranges, indicating excessive supplementation 1
• The tolerable upper intake level (UL) for folic acid is 1000 mcg/day (1 mg/day), established specifically to avoid masking B12 deficiency 1
• Excess folic acid may increase cancer risk and progression, cause insulin resistance, interact with epilepsy medications, and be hepatotoxic, though oral administration at recommended dosages is generally considered non-toxic 1

Critical Safety Concern: Folic Acid Masking B12 Deficiency

The primary reason the UL for folic acid was set at 1 mg/day is to prevent delayed diagnosis of vitamin B12 deficiency and minimize the risk of irreversible neurological complications in B12-deficient individuals 1. While your current B12 level is high, continuing unnecessary folic acid supplementation establishes a dangerous pattern:

• Folic acid can correct the megaloblastic anemia caused by B12 deficiency while allowing neurological manifestations to worsen 1
• If you were to develop true B12 deficiency in the future (from malabsorption, medications like metformin or PPIs, or other causes), ongoing folic acid supplementation could mask the blood picture while irreversible nerve damage progresses 1, 2
• Never administer folic acid before treating vitamin B12 deficiency, as it may precipitate subacute combined degeneration of the spinal cord 2

When Supplementation Is Actually Indicated

B12 Supplementation Is Only Needed For:

• Documented deficiency with B12 <180 pg/mL or borderline levels (180-350 pg/mL) with elevated methylmalonic acid >271 nmol/L 2
• Malabsorption conditions: pernicious anemia, ileal resection >20 cm, Crohn's disease with ileal involvement, post-bariatric surgery 2
• Chronic medication use: metformin >4 months, PPIs >12 months 2
• Strict vegetarian/vegan diet 2
• Age >75 years with documented deficiency 2

Folic Acid Supplementation Is Only Needed For:

• Documented dietary deficiency or chronic hemodialysis: 1-5 mg/day orally 1
• Periconceptional supplementation for women of childbearing age in countries without food fortification: 400 mcg/day 1
• Diseases known to increase folate needs, measured every 3 months until stabilization 1
• Treatment should last four months or until the reason for deficiency is corrected, then maintenance at 330 mcg DFE for adults 1

Monitoring After Stopping Supplements

• Recheck B12 and folate levels in 3-6 months to ensure they normalize to physiologic ranges 2
• If levels remain elevated at 6 months, no further monitoring is needed unless symptoms develop or risk factors emerge 2
• Annual screening is only indicated for high-risk populations: age >75, post-bariatric surgery, ileal resection, Crohn's disease, chronic PPI/metformin use 2

Common Pitfall to Avoid

Do not continue "just to be safe" or because you've been taking them for a long time - this is the most common error in supplement management. Without documented deficiency or a specific indication (malabsorption, dietary restriction, pregnancy planning), continuing supplementation provides no benefit and establishes unnecessary medication burden 1, 2. The research evidence shows no cognitive or functional benefit from folic acid or B12 supplementation in healthy elderly people without deficiency 3, 4, 5.